AMMONIUM UPTAKE BY THE EXTREMITIES AND BRAIN IN HEPATIC COMA, 12

Abstract

Investigations of patients with hepatic cirrhosis and coma have shown that extremities and brain remove ammonium from the circulating blood. This study further evaluates the roles of these peripheral sites in ammonium metabolism as determined by arteriovenous ammonium differences. Extremities and brains of patients without liver disease neither removed nor released ammonium. In patients with liver disease increases in arterial ammonium levels were usually associated with removal of ammonium in proportion to the arterial ammonium concentration. Some alert patients with cirrhosis and some patients in hepatic coma demonstrated poor ammonium removal for the extremities and the brain. Furthermore, in some comatose patients the brains released ammonium. Ammonium removal by extremities and brain was greater in patients in whom coma was associated with an added nitrogen load, e.g., gastrointestinal bleeding, than in those without hemorrhage. The status of peripheral ammonium removal mechanisms may be important in the genesis and outcome of hepatic coma.